Do Now: Which ecological level of organization term(s) include both the biotic and abiotic factors which influence an organism or group of organisms? Use your notebook to review the definition of a “species” and a “population”. Which term would you use to describe the persons living in Montville Township? Explain

You Count! Learn about the Mark and Capture Technique used to estimate the size of a population

Studying Population Size Lab Read and follow all directions step by step. Pencil is recommended. Write your name and partner’s name on the lab. Part 1 must be done before end of period. Be sure to understand what the question is asking before writing. Listen for teacher clarifications during the lab.

Changes to lab apply if you do not think you have the same cup as yesterday… (For Period 4) Continue as if your cup is the same. Follow directions to calculate 20 trial values Then use the second set of data and calculate population size as if it were 10 trials. Then count the actual number in the cup.

Actual population size = 32 Post Lab Discussion Notes: What do the two estimated population sizes tell us about data collecting? Looking at the data… Which number pair reflects the data you obtained? Did your estimated population value increase, decrease or stay the same? 31, 31 28, 31 29, 25 First number represents estimated population size after 10 trials; second number is after 20 trials. Actual population size = 32 Question: Is there a difference between the 10 trials and the 20 trials estimates? How do they compare to the actual? To answer this, you need the actual count. For this example, the actual count is 32 birds in the population. Now answer, the question by comparing the trial values to the actual value. *The values were 31 and 31. It appears that the number of trials does not make a difference. *The values were 28 and 31. It appears that the number of trials brings the estimated population number closer to the actual number. * The values were 29 and 25. It appears that the number of trials moves the estimated population number further away from the actual number. In theory, the greater the number of trials, the closer one gets to the actual value because the total number of individuals (birds) in the sample gets larger. By making the sample size get larger, one minimizes the outside influences.

Post Lab Discussion Notes: What is percent error? Percent Error = (T − E )/T •100 Applied when comparing an experimental quantity, E, with a theoretical quantity, T, which is considered the “correct” value. It is a measure of how inaccurate a measurement is, standardized to how large the measurement is. The percent error is the absolute value of the difference divided by the “correct” value times 100. Look at your percent error for the 20 trials. If you did not get a very low value, like 0-1%, what does that tell you about the technique and the individuals in a population?

R is marked recapture T is total sample size M is marked initially Post Lab Discussion: What makes the estimated population size an acceptable value? Mathematics! Lincoln-Petersen Index R/T = M/N R is marked recapture T is total sample size M is marked initially N is population size This is a proportion and this proportion cannot be upset. So, the number of marked and Unmarked individuals should remain the same throughout the time of investigation.

Listen to another explanation on how to estimate population size Mark and Recapture Video Used for mobile organisms Involves marking a sample of individuals and then estimating population size from the number of marked individuals in subsequent samples the larger the sample, the more accurate

Assumptions Nothing happens to upset the proportions of marked to unmarked birds. The population is a “closed” system. Chance of capturing a marked or unmarked bird is equal. Birds do not lose their marks or tags. There is a sufficient or appropriate amount of time between sampling. If the four assumptions are made, then one can feel comfortable with the estimate population size using the Mark and Recapture Technique

Equal chance for capture Remained marked Think about how birds behave and how people capture animals. For each assumption, can you describe one or two specific ways during the lab when each assumption could have been violated? Violations can explain your percent error value. “Closed” system Equal chance for capture Remained marked Time between sampling is appropriated.

Part 1 Mark and Recapture Technique Conclusion: Estimating population size must take into account the behavior of the organisms, where the organisms live, the way in which the organisms live, mathematical principles, and scientific methods.

Part 2 Sampling Technique Quadrat Sampling Video Organisms in a few small areas are counted and projected to the entire area Used on organisms that are usually sessile animals or plants

Sample Problems: Write formula, plug in values, circle answer There are 30 marked seals.  In a survey, you count 58  seals, 16 of which were  marked.  About how many seals are in the area? A biologist originally marked 40 butterflies in Wilson Park. Over a month long period ­ butterfly traps caught 200 butterflies. Of those 200, 80 were found to have tags. Based on this information, what is the estimated population size of the butterflies in Wilson Park?

Preparing for the Lab Test: Can you… Clearly state the objective or objectives Describe how each of the two techniques are performed Calculate and Explain the purpose of the percent error If given sample data for a given population, determine the estimated population size for each technique Apply knowledge about the techniques to new situations Think of anything else Lab Test on Thursday, 9/22/16 Be sure to have a pen and/or pencil